Background: Chronic inflammation has been recognized in neoplastic disorders, including myeloproliferative neoplasm (MPN), as an important regulator of angiogenesis. Aims: We investigated the influence of vascular endothelial growth factor (VEGF) and pro-inflammatory interleukin-6 (IL-6) on the expression of angiogenic factors, as well as inflammation-related signaling in mononuclear cells (MNC) of patients with MPN and JAK2V617F positive human erythroleukemic (HEL) cells. Results: We found that IL-6 did not change the expression of angiogenic factors in the MNC of patients with MPN and HEL cells. However, IL-6 and the JAK1/2 inhibitor Ruxolitinib significantly increased angiogenic factors—endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor-1 alpha (HIF-1α)—in patients with polycythemia vera (PV). Furthermore, VEGF significantly increased the expression of HIF-1α and eNOS genes, the latter inversely regulated by PI3K and mTOR signaling in the MNC of primary myelofibrosis (PMF). VEGF and inhibitors of inflammatory JAK1/2, PI3K, and mTOR signaling reduced the eNOS protein expression in HEL cells. VEGF also decreased the expression of eNOS and HIF-1α proteins in the MNC of PMF. In contrast, VEGF increased eNOS and HIF-1α protein expression in the MNC of patients with PV, which was mediated by the inflammatory signaling. VEGF increased the level of IL-6 immunopositive MNC of MPN. In summary, VEGF conversely regulated gene and protein expression of angiogenic factors in the MNC of PMF, while VEGF increased angiogenic factor expression in PV mediated by the inflammation-related signaling. Conclusion: The angiogenic VEGF induction of IL-6 supports chronic inflammation that, through positive feedback, further promotes angiogenesis with concomitant JAK1/2 inhibition.

In several systems, hydroxyurea has been shown to trigger nitric oxide (NO) release or activation of NO synthase (NOS). To elucidate this duality in its pharmacological effects, during myelosuppression, we individually examined hydroxyurea’s (NO releasing agent) and NO metabolites’ (stable NO degradation products) effects on erythroid colony growth and NOS/NO levels in mice using NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). Hydroxyurea and nitrite/nitrate decreased the bone marrow cellularity that was blocked by PTIO only for the NO metabolites. Hydroxyurea inhibition of colony-forming unit-erythroid (CFU-E) formation and reticulocytes was reversed by PTIO. Moreover, hydroxyurea, through a negative feedback mechanism, reduced inducible NOS (iNOS) expressing cells in CFU-E, also prevented by PTIO. Nitrate inhibition of burst-forming units-erythroid (BFU-E) colony growth was blocked by PTIO, but not in mature CFU-E. The presented results reveal that NO release and/or production mediates the hydroxyurea inhibition of mature erythroid colony growth and the frequency of iNOS immunoreactive CFU-E.

The calcium-binding proteins S100A4, S100A8, and S100A9 are upregulated in chronic lymphocytic leukemia (CLL), while the S100A9 promotes NF-κB activity during disease progression. The S100-protein family has been involved in several malignancies as mediators of inflammation and proliferation. The hypothesis of our study is that S100A proteins are mediators in signaling pathways associated with inflammation-induced proliferation, such as NF-κB, PI3K/AKT, and JAK/STAT. The mononuclear cells (MNCs) of CLL were treated with proinflammatory IL-6, anti-inflammatory IL-10 cytokines, inhibitors of JAK1/2, NF-κB, and PI3K signaling pathways, to evaluate S100A4, S100A8, S100A9, and S100A12 expression as well as NF-κB activation by qRT-PCR, immunocytochemistry, and immunoblotting. The quantity of S100A4, S100A8, and S100A9 positive cells (p < 0.05) and their protein expression (p < 0.01) were significantly decreased in MNCs of CLL patients compared to healthy controls. The S100A levels were generally increased in CD19⁺ cells compared to MNCs of CLL. The S100A4 gene expression was significantly stimulated (p < 0.05) by the inhibition of the PI3K/AKT signaling pathway in MNCs. IL-6 stimulated S100A4 and S100A8 protein expression, prevented by the NF-κB and JAK1/2 inhibitors. In contrast, IL-10 reduced S100A8, S100A9, and S100A12 protein expressions in MNCs of CLL. Moreover, IL-10 inhibited activation of NF-κB signaling (4-fold, p < 0.05). In conclusion, inflammation stimulated the S100A protein expression mediated via the proliferation-related signaling and balanced by the cytokines in CLL.

Chronic inflammation is characterized by the production of reactive oxygen species (ROS), reactive nitrogen species, and inflammatory cytokines in myeloproliferative neoplasms (MPNs). In addition to these parameters, the aim of this study was to analyze the influence of ROS on the proliferation-related AKT/mTOR signaling pathway and the relationship with inflammatory factors in chronic myelogenous leukemia (CML). The activity of the antioxidant enzymes superoxide dismutase, glutathione peroxidase, and catalase is reduced in erythrocytes while levels of the oxidative stress markers malondialdehyde and protein carbonyl are elevated in the plasma of patients with CML. In addition, nitrogen species (nitrotyrosine, iNOS, eNOS) and inflammation markers (IL-6, NFkB, and S100 protein) were increased in granulocytes of CML while anti-inflammatory levels of IL-10 were decreased in plasma. CML granulocytes exhibited greater resistance to cytotoxic H₂O₂ activity compared to healthy subjects. Moreover, phosphorylation of the apoptotic p53 protein was reduced while the activity of the AKT/mTOR signaling pathway was increased, which was further enhanced by oxidative stress (H₂O₂) in granulocytes and erythroleukemic K562 cells. IL-6 caused oxidative stress and DNA damage that was mitigated using antioxidant or inhibition of inflammatory NFkB transcription factor in K562 cells. We demonstrated the presence of oxidative and nitrosative stress in CML, with the former mediated by AKT/mTOR signaling and stimulated by inflammation.

Hydroxyurea (HU) is an antineoplastic agent that functions as an antimetabolite compound by inhibiting the ribonucleotide reductase. HU acts mainly as a cytostatic drug that through DNA replication stress may trigger a premature senescence-like cell phenotype, though its influence on bone marrow-derived mesenchymal stem/stromal cell (BMMSC) functions has not elucidated yet. Our results indicate that HU inhibits the growth of human BMMSC alongside senescence-like changes in both morphology and replicative potential, provokes cell cycle arrest at the S phase without affecting cellular viability and induces the expression of senescence-associated β-galactosidase and p16INK4. Moreover, HU-induced senescent BMMSC, although they did not change MSC markers expression, exhibited reduced capacity osteogenic and adipogenic differentiation. Conversely, HU treatment increased immunoregulatory functions of BMMSC compared with untreated cells and determined by T-cell proliferation. Interestingly, HU did not influence the capacity of BMMSC to induce monocytic myeloid-derived suppressor cells. Thus, these results suggest that HU improves the BMMSC functions on the T-cell inhibition and preserves their interaction with myeloid cell compartment. Mechanistically, BMMSC under HU treatment displayed a downregulation of mTOR and p38 MAPK signaling that may explain the reduced cell differentiation and increased immunomodulation activities. Together, the results obtained in this investigation suggest that HU by inducing senescence-like phenotype of BMMSC influences their cellular differentiation and immunoregulatory functions.

Cancer-promoting proinflammatory microenvironment influences colorectal cancer (CRC) development. We examined the biomarkers of inflammation, intestinal differentiation, and DNA activity correlated with the clinical parameters to observe progression and prognosis in the adenocarcinoma subtype of CRC. Their immunohistology, immunoblotting, and RT-PCR analyses were performed in the adenocarcinoma and neighboring healthy tissues of 64 patients with CRC after routine colorectal surgery. Proinflammatory nuclear factor kappa B (NFκB) signaling as well as interleukin 6 (IL-6) and S100 protein levels were upregulated in adenocarcinoma compared with nearby healthy colon tissue. In contrast to nitrotyrosine expression, the oxidative stress marker 8-Hydroxy-2′-deoxyguanosine (8-OHdG) was increased in adenocarcinoma tissue. Biomarkers of intestinal differentiation β-catenin and mucin 2 (MUC2) were inversely regulated, with the former upregulated in adenocarcinoma tissue and positively correlated with tumor marker CA19-9. Downregulation of MUC2 expression correlated with the increased 2-year survival rate of patients with CRC. Proliferation-related mammalian target of rapamycin (mTOR) signaling was activated, and Ki67 frequency was three-fold augmented in positive correlation with metastasis and cancer stage, respectively. Conclusion: We demonstrated a parallel induction of oxidative stress and inflammation biomarkers in adenocarcinoma tissue that was not reflected in the neighboring healthy colon tissue of CRC. The expansiveness of colorectal adenocarcinoma was confirmed by irregular intestinal differentiation and elevated proliferation biomarkers, predominantly Ki67. The origin of the linked inflammatory factors was in adenocarcinoma tissue, with an accompanying systemic immune response.